// --- Copyright (c) 2006-2008 Stefan Kyntchev ---
// This software is written and copyrighted by Stefan Kyntchev 
// and BeyondPod Team members. All rights are reserved.
// Author contact: support@beyondpod.mobi
// ------------------------------------------------------------------------
// This file is part of BeyondPod RSS Feed Reader and Podcast manager
// (www.codeplex.com/BeyondPod) 
// BeyondPod is free software: you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published by 
// the Free Software Foundation, either version 3 of the License, or 
// (at your option) any later version. 
//  
// BeyondPod is distributed in the hope that it will be useful, 
// but WITHOUT ANY WARRANTY; without even the implied warranty of 
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
// GNU General Public License for more details. 
//  
// You should have received a copy of the GNU General Public License
// along with BeyondPod. If not, see <http://www.gnu.org/licenses/>
// ------------------------------------------------------------------------
// COPYRIGHT NOTICE: This copyright notice may NOT be removed, obscured or modified 
// without written consent from the author.
// --- End copyright notice --- 


using System;
using System.Collections;
using System.Globalization;
using System.IO;
using System.Text;

namespace svs.Mobile.BeyondMedia.FeedCore.Helpers
{
	public sealed class HttpUtility
	{
		#region Fields

		private const string _hex = "0123456789ABCDEF";
		private const string _chars = "<>;:.?=&@*+%/\\";
		private static Hashtable entities;

		#endregion // Fields

		#region Constructors

		static HttpUtility()
		{
			// Build the hash table of HTML entity references. This list comes
			// from the HTML 4.01 W3C recommendation.
			entities = new Hashtable();
			entities.Add("nbsp", '\u00A0');
			entities.Add("iexcl", '\u00A1');
			entities.Add("cent", '\u00A2');
			entities.Add("pound", '\u00A3');
			entities.Add("curren", '\u00A4');
			entities.Add("yen", '\u00A5');
			entities.Add("brvbar", '\u00A6');
			entities.Add("sect", '\u00A7');
			entities.Add("uml", '\u00A8');
			entities.Add("copy", '\u00A9');
			entities.Add("ordf", '\u00AA');
			entities.Add("laquo", '\u00AB');
			entities.Add("not", '\u00AC');
			entities.Add("shy", '\u00AD');
			entities.Add("reg", '\u00AE');
			entities.Add("macr", '\u00AF');
			entities.Add("deg", '\u00B0');
			entities.Add("plusmn", '\u00B1');
			entities.Add("sup2", '\u00B2');
			entities.Add("sup3", '\u00B3');
			entities.Add("acute", '\u00B4');
			entities.Add("micro", '\u00B5');
			entities.Add("para", '\u00B6');
			entities.Add("middot", '\u00B7');
			entities.Add("cedil", '\u00B8');
			entities.Add("sup1", '\u00B9');
			entities.Add("ordm", '\u00BA');
			entities.Add("raquo", '\u00BB');
			entities.Add("frac14", '\u00BC');
			entities.Add("frac12", '\u00BD');
			entities.Add("frac34", '\u00BE');
			entities.Add("iquest", '\u00BF');
			entities.Add("Agrave", '\u00C0');
			entities.Add("Aacute", '\u00C1');
			entities.Add("Acirc", '\u00C2');
			entities.Add("Atilde", '\u00C3');
			entities.Add("Auml", '\u00C4');
			entities.Add("Aring", '\u00C5');
			entities.Add("AElig", '\u00C6');
			entities.Add("Ccedil", '\u00C7');
			entities.Add("Egrave", '\u00C8');
			entities.Add("Eacute", '\u00C9');
			entities.Add("Ecirc", '\u00CA');
			entities.Add("Euml", '\u00CB');
			entities.Add("Igrave", '\u00CC');
			entities.Add("Iacute", '\u00CD');
			entities.Add("Icirc", '\u00CE');
			entities.Add("Iuml", '\u00CF');
			entities.Add("ETH", '\u00D0');
			entities.Add("Ntilde", '\u00D1');
			entities.Add("Ograve", '\u00D2');
			entities.Add("Oacute", '\u00D3');
			entities.Add("Ocirc", '\u00D4');
			entities.Add("Otilde", '\u00D5');
			entities.Add("Ouml", '\u00D6');
			entities.Add("times", '\u00D7');
			entities.Add("Oslash", '\u00D8');
			entities.Add("Ugrave", '\u00D9');
			entities.Add("Uacute", '\u00DA');
			entities.Add("Ucirc", '\u00DB');
			entities.Add("Uuml", '\u00DC');
			entities.Add("Yacute", '\u00DD');
			entities.Add("THORN", '\u00DE');
			entities.Add("szlig", '\u00DF');
			entities.Add("agrave", '\u00E0');
			entities.Add("aacute", '\u00E1');
			entities.Add("acirc", '\u00E2');
			entities.Add("atilde", '\u00E3');
			entities.Add("auml", '\u00E4');
			entities.Add("aring", '\u00E5');
			entities.Add("aelig", '\u00E6');
			entities.Add("ccedil", '\u00E7');
			entities.Add("egrave", '\u00E8');
			entities.Add("eacute", '\u00E9');
			entities.Add("ecirc", '\u00EA');
			entities.Add("euml", '\u00EB');
			entities.Add("igrave", '\u00EC');
			entities.Add("iacute", '\u00ED');
			entities.Add("icirc", '\u00EE');
			entities.Add("iuml", '\u00EF');
			entities.Add("eth", '\u00F0');
			entities.Add("ntilde", '\u00F1');
			entities.Add("ograve", '\u00F2');
			entities.Add("oacute", '\u00F3');
			entities.Add("ocirc", '\u00F4');
			entities.Add("otilde", '\u00F5');
			entities.Add("ouml", '\u00F6');
			entities.Add("divide", '\u00F7');
			entities.Add("oslash", '\u00F8');
			entities.Add("ugrave", '\u00F9');
			entities.Add("uacute", '\u00FA');
			entities.Add("ucirc", '\u00FB');
			entities.Add("uuml", '\u00FC');
			entities.Add("yacute", '\u00FD');
			entities.Add("thorn", '\u00FE');
			entities.Add("yuml", '\u00FF');
			entities.Add("fnof", '\u0192');
			entities.Add("Alpha", '\u0391');
			entities.Add("Beta", '\u0392');
			entities.Add("Gamma", '\u0393');
			entities.Add("Delta", '\u0394');
			entities.Add("Epsilon", '\u0395');
			entities.Add("Zeta", '\u0396');
			entities.Add("Eta", '\u0397');
			entities.Add("Theta", '\u0398');
			entities.Add("Iota", '\u0399');
			entities.Add("Kappa", '\u039A');
			entities.Add("Lambda", '\u039B');
			entities.Add("Mu", '\u039C');
			entities.Add("Nu", '\u039D');
			entities.Add("Xi", '\u039E');
			entities.Add("Omicron", '\u039F');
			entities.Add("Pi", '\u03A0');
			entities.Add("Rho", '\u03A1');
			entities.Add("Sigma", '\u03A3');
			entities.Add("Tau", '\u03A4');
			entities.Add("Upsilon", '\u03A5');
			entities.Add("Phi", '\u03A6');
			entities.Add("Chi", '\u03A7');
			entities.Add("Psi", '\u03A8');
			entities.Add("Omega", '\u03A9');
			entities.Add("alpha", '\u03B1');
			entities.Add("beta", '\u03B2');
			entities.Add("gamma", '\u03B3');
			entities.Add("delta", '\u03B4');
			entities.Add("epsilon", '\u03B5');
			entities.Add("zeta", '\u03B6');
			entities.Add("eta", '\u03B7');
			entities.Add("theta", '\u03B8');
			entities.Add("iota", '\u03B9');
			entities.Add("kappa", '\u03BA');
			entities.Add("lambda", '\u03BB');
			entities.Add("mu", '\u03BC');
			entities.Add("nu", '\u03BD');
			entities.Add("xi", '\u03BE');
			entities.Add("omicron", '\u03BF');
			entities.Add("pi", '\u03C0');
			entities.Add("rho", '\u03C1');
			entities.Add("sigmaf", '\u03C2');
			entities.Add("sigma", '\u03C3');
			entities.Add("tau", '\u03C4');
			entities.Add("upsilon", '\u03C5');
			entities.Add("phi", '\u03C6');
			entities.Add("chi", '\u03C7');
			entities.Add("psi", '\u03C8');
			entities.Add("omega", '\u03C9');
			entities.Add("thetasym", '\u03D1');
			entities.Add("upsih", '\u03D2');
			entities.Add("piv", '\u03D6');
			entities.Add("bull", '\u2022');
			entities.Add("hellip", '\u2026');
			entities.Add("prime", '\u2032');
			entities.Add("Prime", '\u2033');
			entities.Add("oline", '\u203E');
			entities.Add("frasl", '\u2044');
			entities.Add("weierp", '\u2118');
			entities.Add("image", '\u2111');
			entities.Add("real", '\u211C');
			entities.Add("trade", '\u2122');
			entities.Add("alefsym", '\u2135');
			entities.Add("larr", '\u2190');
			entities.Add("uarr", '\u2191');
			entities.Add("rarr", '\u2192');
			entities.Add("darr", '\u2193');
			entities.Add("harr", '\u2194');
			entities.Add("crarr", '\u21B5');
			entities.Add("lArr", '\u21D0');
			entities.Add("uArr", '\u21D1');
			entities.Add("rArr", '\u21D2');
			entities.Add("dArr", '\u21D3');
			entities.Add("hArr", '\u21D4');
			entities.Add("forall", '\u2200');
			entities.Add("part", '\u2202');
			entities.Add("exist", '\u2203');
			entities.Add("empty", '\u2205');
			entities.Add("nabla", '\u2207');
			entities.Add("isin", '\u2208');
			entities.Add("notin", '\u2209');
			entities.Add("ni", '\u220B');
			entities.Add("prod", '\u220F');
			entities.Add("sum", '\u2211');
			entities.Add("minus", '\u2212');
			entities.Add("lowast", '\u2217');
			entities.Add("radic", '\u221A');
			entities.Add("prop", '\u221D');
			entities.Add("infin", '\u221E');
			entities.Add("ang", '\u2220');
			entities.Add("and", '\u2227');
			entities.Add("or", '\u2228');
			entities.Add("cap", '\u2229');
			entities.Add("cup", '\u222A');
			entities.Add("int", '\u222B');
			entities.Add("there4", '\u2234');
			entities.Add("sim", '\u223C');
			entities.Add("cong", '\u2245');
			entities.Add("asymp", '\u2248');
			entities.Add("ne", '\u2260');
			entities.Add("equiv", '\u2261');
			entities.Add("le", '\u2264');
			entities.Add("ge", '\u2265');
			entities.Add("sub", '\u2282');
			entities.Add("sup", '\u2283');
			entities.Add("nsub", '\u2284');
			entities.Add("sube", '\u2286');
			entities.Add("supe", '\u2287');
			entities.Add("oplus", '\u2295');
			entities.Add("otimes", '\u2297');
			entities.Add("perp", '\u22A5');
			entities.Add("sdot", '\u22C5');
			entities.Add("lceil", '\u2308');
			entities.Add("rceil", '\u2309');
			entities.Add("lfloor", '\u230A');
			entities.Add("rfloor", '\u230B');
			entities.Add("lang", '\u2329');
			entities.Add("rang", '\u232A');
			entities.Add("loz", '\u25CA');
			entities.Add("spades", '\u2660');
			entities.Add("clubs", '\u2663');
			entities.Add("hearts", '\u2665');
			entities.Add("diams", '\u2666');
			entities.Add("quot", '\u0022');
			entities.Add("amp", '\u0026');
			entities.Add("lt", '\u003C');
			entities.Add("gt", '\u003E');
			entities.Add("OElig", '\u0152');
			entities.Add("oelig", '\u0153');
			entities.Add("Scaron", '\u0160');
			entities.Add("scaron", '\u0161');
			entities.Add("Yuml", '\u0178');
			entities.Add("circ", '\u02C6');
			entities.Add("tilde", '\u02DC');
			entities.Add("ensp", '\u2002');
			entities.Add("emsp", '\u2003');
			entities.Add("thinsp", '\u2009');
			entities.Add("zwnj", '\u200C');
			entities.Add("zwj", '\u200D');
			entities.Add("lrm", '\u200E');
			entities.Add("rlm", '\u200F');
			entities.Add("ndash", '\u2013');
			entities.Add("mdash", '\u2014');
			entities.Add("lsquo", '\u2018');
			entities.Add("rsquo", '\u2019');
			entities.Add("sbquo", '\u201A');
			entities.Add("ldquo", '\u201C');
			entities.Add("rdquo", '\u201D');
			entities.Add("bdquo", '\u201E');
			entities.Add("dagger", '\u2020');
			entities.Add("Dagger", '\u2021');
			entities.Add("permil", '\u2030');
			entities.Add("lsaquo", '\u2039');
			entities.Add("rsaquo", '\u203A');
			entities.Add("euro", '\u20AC');
		}

		#endregion // Constructors

		#region Methods

		public static void HtmlAttributeEncode(string s, TextWriter output)
		{
			output.Write(HtmlAttributeEncode(s));
		}

		public static string HtmlAttributeEncode(string s)
		{
			if (null == s)
				return null;

			StringBuilder output = new
				StringBuilder();

			foreach (char c in s)
				switch (c)
				{
					case '&':
						output.Append("&");
						break;

					case '"':
						output.Append("\"");
						break;
					default:

						output.Append(c);
						break;
				}

			return output.ToString();
		}

		public static string UrlDecode(string str)
		{
			return UrlDecode(str,
			                 Encoding.UTF8);
		}

		private static char[] GetChars(MemoryStream b, Encoding e)
		{
			return e.GetChars(b.GetBuffer(),
			                  0, (int) b.Length);
		}

		public static string UrlDecode(string s, Encoding e)
		{
			if (null == s)
				return null;

			if (e == null)
				e = Encoding.UTF8;

			StringBuilder output = new
				StringBuilder();
			long len = s.Length;
			NumberStyles hexa = NumberStyles.HexNumber;
			MemoryStream bytes = new MemoryStream();

			for (int i = 0; i < len; i++)
			{
				if (s[i] == '%' && i + 2
				                   < len)
				{
					if (s[i + 1]
					    == 'u' && i + 5 < len)
					{
						if
							(bytes.Length > 0)
						{
							output.Append(GetChars(bytes, e));

							bytes.SetLength(0);
						}

						output.Append((char) Int32.Parse(s.Substring(i + 2, 4), hexa));
						i += 5;
					}
					else
					{
						bytes.WriteByte((byte) Int32.Parse(s.Substring(i + 1, 2), hexa));
						i += 2;
					}
					continue;
				}

				if (bytes.Length > 0)
				{
					output.Append
						(GetChars(bytes, e));
					bytes.SetLength
						(0);
				}

				if (s[i] == '+')
				{
					output.Append
						(' ');
				}
				else
				{
					output.Append(s
					              	[i]);
				}
			}

			if (bytes.Length > 0)
			{
				output.Append(GetChars
				              	(bytes, e));
			}

			return output.ToString();
		}

		public static string UrlDecode(byte[] bytes, Encoding e)
		{
			if (bytes == null)
				return null;

			return UrlDecode(bytes, 0,
			                 bytes.Length, e);
		}

		private static int GetInt(byte b)
		{
			char c = Char.ToUpper((char) b);
			if (c >= '0' && c <= '9')
				return c - '0';

			if (c < 'A' || c > 'F')
				return 0;

			return (c - 'A' + 10);
		}

		private static char GetChar(byte[] bytes, int offset, int length)
		{
			int value = 0;
			int end = length + offset;
			for (int i = offset; i < end; i++)
				value = (value << 4) +
				        GetInt(bytes[offset]);

			return (char) value;
		}

		public static string UrlDecode(byte[] bytes, int offset, int count, Encoding e)
		{
			if (bytes == null || count == 0)
				return null;

			if (bytes == null)
				throw new
					ArgumentNullException("bytes");

			if (offset < 0 || offset >
			                  bytes.Length)
				throw new
					ArgumentOutOfRangeException("offset");

			if (count < 0 || offset + count >
			                 bytes.Length)
				throw new
					ArgumentOutOfRangeException("count");

			StringBuilder output = new
				StringBuilder();
			MemoryStream acc = new
				MemoryStream();

			int end = count + offset;
			for (int i = offset; i < end; i++)
			{
				if (bytes[i] == '%' && i
				                       + 2 < count)
				{
					if (bytes[i + 1]
					    == (byte) 'u' && i + 5 < end)
					{
						if
							(acc.Length > 0)
						{
							output.Append(GetChars(acc, e));

							acc.SetLength(0);
						}

						output.Append(GetChar(bytes, offset + 2, 4));
						i += 5;
					}
					else
					{
						acc.WriteByte((byte) GetChar(bytes, offset + 1,
						                             2));
						i += 2;
					}
					continue;
				}

				if (acc.Length > 0)
				{
					output.Append
						(GetChars(acc, e));
					acc.SetLength(0);
				}

				if (bytes[i] == '+')
				{
					output.Append
						(' ');
				}
				else
				{
					output.Append
						((char) bytes[i]);
				}
			}

			if (acc.Length > 0)
			{
				output.Append(GetChars
				              	(acc, e));
			}

			return output.ToString();
		}

		public static byte[] UrlDecodeToBytes(byte[] bytes)
		{
			if (bytes == null)
				return null;

			return UrlDecodeToBytes(bytes, 0,
			                        bytes.Length);
		}

		public static byte[] UrlDecodeToBytes(string str)
		{
			return UrlDecodeToBytes(str,
			                        Encoding.UTF8);
		}

		public static byte[] UrlDecodeToBytes(string str, Encoding e)
		{
			if (str == null)
				return null;

			if (e == null)
				throw new
					ArgumentNullException("e");

			return UrlDecodeToBytes
				(e.GetBytes(str));
		}

		public static byte[] UrlDecodeToBytes(byte[] bytes, int offset, int count)
		{
			if (bytes == null)
				return null;

			int len = bytes.Length;
			if (offset < 0 || offset >= len)
				throw new
					ArgumentOutOfRangeException("offset");

			if (count < 0 || offset <= len -
			                           count)
				throw new
					ArgumentOutOfRangeException("count");

			ArrayList result = new ArrayList
				();
			int end = offset + count;
			for (int i = offset; i < end; i++)
			{
				char c = (char) bytes[i];
				if (c == '+')
					c = ' ';
				else if (c == '%' && i <
				                     end - 2)
				{
					c = GetChar
						(bytes, i, 2);
					i += 2;
				}
				result.Add((byte) c);
			}

			return (byte[]) result.ToArray
			                	(typeof (byte));
		}

		public static string UrlEncode(string str)
		{
			return UrlEncode(str,
			                 Encoding.UTF8);
		}

		public static string UrlEncode(string s,Encoding Enc)
		{
			if (s == null)
				return null;

			if (s == "")
				return "";

			byte[] bytes = Enc.GetBytes(s);
			bytes = UrlEncodeToBytes(bytes,
			                         0, bytes.Length);
			return Encoding.ASCII.GetString
				(bytes, 0, bytes.Length);
		}

		public static string UrlEncode(byte[]bytes)
		{
			if (bytes == null)
				return null;

			if (bytes.Length == 0)
				return "";
			bytes = UrlEncodeToBytes(bytes,
			                         0, bytes.Length);
			return Encoding.ASCII.GetString
				(bytes, 0, bytes.Length);
		}

		public static string UrlEncode(byte[] bytes, int offset, int count)
		{
			if (bytes == null)
				return null;

			if (bytes.Length == 0)
				return "";
			bytes = UrlEncodeToBytes(bytes,
			                         offset, count);
			return Encoding.ASCII.GetString
				(bytes, 0, bytes.Length);
		}

		public static byte[] UrlEncodeToBytes(string str)
		{
			return UrlEncodeToBytes(str,
			                        Encoding.UTF8);
		}

		public static byte[] UrlEncodeToBytes(string str, Encoding e)
		{
			if (str == null)
				return null;

			if (str == "")
				return new byte[0];

			byte[] bytes = e.GetBytes(str);
			return UrlEncodeToBytes(bytes, 0,
			                        bytes.Length);
		}

		public static byte[] UrlEncodeToBytes(byte[] bytes)
		{
			if (bytes == null)
				return null;

			if (bytes.Length == 0)
				return new byte[0];

			return UrlEncodeToBytes(bytes, 0,
			                        bytes.Length);
		}

		private static readonly char[] hexChars = "0123456789ABCDEF".ToCharArray();

		public static byte[] UrlEncodeToBytes(byte[] bytes, int offset, int count)
		{
			if (bytes == null)
				return null;

			int len = bytes.Length;
			if (len == 0)
				return new byte[0];

			if (offset < 0 || offset >= len)
				throw new
					ArgumentOutOfRangeException("offset");

			if (count < 0 || offset < len -
			                          count)
				throw new
					ArgumentOutOfRangeException("count");

			ArrayList result = new ArrayList
				();
			int end = offset + count;
			for (int i = offset; i < end; i++)
			{
				char c = (char) bytes[i];
				if (c == ' ')
					result.Add
						((byte) '+');
				else if ((c < '0' && c != '-' && c != '.') ||
				         (c < 'A' && c
				                     > '9') ||
				         (c > 'Z' && c
				                     < 'a' && c != '_') ||
				         (c > 'z'))
				{
					result.Add
						((byte) '%');
					int idx = ((int)
					           c) >> 4;
					result.Add((byte)
					           hexChars[idx]);
					idx = (c) &
					      0x0F;
					result.Add((byte)
					           hexChars[idx]);
				}
				else
				{
					result.Add((byte)c);
				}
			}
			return (byte[])result.ToArray(typeof(byte));
		}

		public static string UrlEncodeUnicode(string str)
		{
			if (str == null)
				return null;

			StringBuilder result = new
				StringBuilder();
			int end = str.Length;
			for (int i = 0; i < end; i++)
			{
				int idx;
				char c = str[i];
				if (c == ' ')
				{
					result.Append
						('+');
					continue;
				}

				if (c > 255)
				{
					result.Append("%u");
					idx = ((int) c) >>
					      24;
					result.Append
						(hexChars[idx]);
					idx = (((int) c)
					       >> 16) & 0x0F;
					result.Append
						(hexChars[idx]);
					idx = (((int) c)
					       >> 8) & 0x0F;
					result.Append
						(hexChars[idx]);
					idx = (c) &
					      0x0F;
					result.Append
						(hexChars[idx]);
					continue;
				}

				if ((c < '0' && c != '-'
				     && c != '.') ||
				    (c < 'A' && c
				                > '9') ||
				    (c > 'Z' && c
				                < 'a' && c != '_') ||
				    (c > 'z'))
				{
					result.Append
						('%');
					idx = ((int) c) >>
					      4;
					result.Append
						(hexChars[idx]);
					idx = (c) &
					      0x0F;
					result.Append
						(hexChars[idx]);
					continue;
				}

				result.Append(c);
			}

			return result.ToString();
		}

		public static byte[] UrlEncodeUnicodeToBytes(string str)
		{
			if (str == null)
				return null;

			if (str == "")
				return new byte[0];

			return Encoding.ASCII.GetBytes
				(UrlEncodeUnicode(str));
		}

		/// <summary>
		/// Decodes an HTML-encoded string and returns the decoded string.
		/// </summary>
		/// <param name="s">The HTML string to decode. </param>
		/// <returns>The decoded text.</returns>
		public static string HtmlDecode(string s)
		{
			if (s == null)
				throw new
					ArgumentNullException("s");

			bool insideEntity = false; // used to indicate that we are in a potential entity
			string entity = String.Empty;
			StringBuilder output = new
				StringBuilder();

			foreach (char c in s)
			{
				switch (c)
				{
					case '&':

						output.Append(entity);
						entity
							= "&";

						insideEntity = true;
						break;
					case ';':
						if (!
						    insideEntity)
						{
							output.Append(c);

							break;
						}

						entity +=
							c;
						int length
							= entity.Length;
						if (length
						    >= 2 && entity[1] == '#' && entity[2] != ';')

							entity = ((char) Int32.Parse(entity.Substring(2,
							                                              entity.Length - 3))).ToString();
						else if
							(length > 1 && entities.ContainsKey(entity.Substring(1,
							                                                     entity.Length - 2)))

							entity = entities[entity.Substring(1,
							                                   entity.Length - 2)].ToString();


						output.Append(entity);
						entity =
							String.Empty;

						insideEntity = false;
						break;
					default:
						if
							(insideEntity)

							entity += c;
						else

							output.Append(c);
						break;
				}
			}
			output.Append(entity);
			return output.ToString();
		}

		/// <summary>
		/// Decodes an HTML-encoded string and sends the resulting output to a TextWriter  output stream.
		/// </summary>
		/// <param name="s">The HTML string to decode</param>
		/// <param name="output">The TextWriter output stream containing the decoded string . </param>
		public static void HtmlDecode(string s,TextWriter output)
		{
			output.Write(HtmlDecode(s));
		}

		/// <summary>
		/// HTML-encodes a string and returns the encoded string.
		/// </summary>
		/// <param name="s">The text string to encode . </param>
		/// <returns>The HTML-encoded text .</ returns>
		public static string HtmlEncode(string s)
		{
			if (s == null)
				throw new
					ArgumentNullException("s");

			StringBuilder output = new
				StringBuilder();

			foreach (char c in s)
				switch (c)
				{
					case '&':

						output.Append("&");
						break;
					case '>':

						output.Append(">");
						break;
					case '<':

						output.Append("<");
						break;
					case '"':

						output.Append("\"");
						break;
					default:
						if (c > 128)
						{
							output.Append("&#");

							output.Append(((int) c).ToString());

							output.Append(";");
						}
						else

							output.Append(c);
						break;
				}
			return output.ToString();
		}

		/// <summary>
		/// HTML-encodes a string and sends the resulting output to a TextWriter output stream . 
		/// </summary>
		/// <param name="s">The string to encode.</param>
		/// <param name="output">The TextWriter output stream containing the encoded string . </param>
		public static void HtmlEncode(string s,TextWriter output)
		{
			output.Write(HtmlEncode(s));
		}

		#endregion // Methods
	}
}